Materials and Methods

17 subjects, implanted with a CII-Bionic EarÂ® or a HiRes90KTM were included. NRI was measured on four electrodes, intra-operatively, at first fitting, and after three and six months of use. The SoundWaveÂ® fitting software was used to record NRI, typically on stimulating/recording pairs 3/1, 7/5, 11/9, 15/13. eSRT recordings were performed intra-operatively, with SoundWaveÂ® speech bursts. Additionally, as new software enables the use of banded stimuli to elicit eCAPs, multi-channel NRI was measured post-operatively. Subjects were fitted using the SoundWaveÂ® defaults i.e. speech bursts and automatic calculation of thresholds (Ts): 10% of most comfortable levels (Ms).

Results

Relationships between NRI thresholds (tNRI), eSRT and Ms are presented. Results to date show that first fitting Ms are 65 % of intra-operative tNRI; stable Ms (three months of implant use) are equal to 85% of intra-operative tNRI. In patients with lower intraoperative tNRI levels, Ms levels are closer to tNRI. eSRT values appear better correlated to stable Ms. Preliminary results with multi-channel NRI show that responses have steeper growth functions and lower thresholds than single channel measures.

Conclusions

The results show that single channel tNRI and eSRT values can be clinically useful for programming. The banded NRI data is even more encouraging: similar to the speech bursts, the banded stimuli seem to generate responses better correlated to fitting parameters. The next step is to compare NRI- and eSRT-based programs to current fittings.